Calculating Elastic Energy: Where Did I Go Wrong?

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SUMMARY

The discussion centers on the calculation of elastic energy using the formula E=σε/2. The user initially calculated ε as 4*10^-3 and σ as 4.4*10^9, leading to an energy value of 880,000 J. However, the correct answer is 35.2 J, indicating a significant error in unit conversion and the interpretation of stored energy per unit volume. The key takeaway is the importance of unit consistency in calculations.

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  • Understanding of elastic energy concepts
  • Familiarity with the equation E=σε/2
  • Knowledge of unit conversions in physics
  • Basic principles of stress and strain in materials
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  • Review unit conversion techniques in physics
  • Study the relationship between stress (σ) and strain (ε)
  • Learn about elastic potential energy in materials
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Students studying physics, particularly those focusing on mechanics and material science, as well as educators looking to clarify concepts related to elastic energy calculations.

Clara Chung
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Homework Statement


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Homework Equations

The Attempt at a Solution


I tried to use the equation introduced in the class, E=σε/2
ε=αΔT =2*10-5*200 = 4*10-3
and by σ=Yε, I get σ=110*109*4*10-3 = 4.4*109
so E=(4*10-3) * (4.4*109 ) /2 = 880000J
Why am I wrong?
The correct answer is 35.2 J
 

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Better check your units. Also, you determined the stored energy per unit volume.
 
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Chestermiller said:
Better check your units. Also, you determined the stored energy per unit volume.
Thanks!
 

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